This invention relates to evaporative coolers and more particularly to evaporative coolers specially adapted to cool pouches containing liquid or semi-liquid materials such as tomato paste or the like.
Pouches of tomato paste are typically subjected to a heating process to perform a biological kill on the material to preserve the product. After the biological kill has been performed it is important that the heat be quickly removed from the product so that the heat does not overcook or burn the product.
In one popular form of prior art cooler, the pouches are routed through a series of conveyor assemblies positioned one above the other. As the pouches move across the conveyors they are sprayed with water and a high volume flow of air is drawn into one side of the conveyor housing and discharged from the other side of the housing. The combination of the spray and the air flow across the pouches causes an evaporative cooling effect.
Typically the pouches comprise a flexible plastic pouch and the pouches are loaded into the end of the uppermost conveyor of the conveyor system whereafter the pouches travel along the upper conveyor where they are sprayed with water in the moving airstream. When the pouches reach the end of the conveyor they are discharged downwardly from the discharge end of the upper conveyor onto the feed end of the next lower conveyor for subsequent movement through the cooler. It is important that the transfer of the pouches from the discharge end of the upper conveyor and the feed end of the next lower conveyor be carefully controlled so as not to ball up the pouches or rupture the pouches in the transfer process. Various arrangements have been proposed in the prior art to facilitate this transfer.
According to one prior art transfer proposal, the pouches are directed to the next lower conveyor through a slide mechanism wherein, when the pouches reach the end of the upper conveyor, they drop off the discharge end of the upper conveyor and are directed onto an inclined slide which serves to direct the pouch to the feed end of the next lower conveyor. This arrangement has a number of disadvantages. First, the orientation of the pouches changes when they hit the slide and again when they arrive at the end of the slide and hit the next lower conveyor. Because the bags are flexible they tend to twist, puff or otherwise distort during the transfer from one conveyor to the next. Additionally, the pouches tend to bunch up on the slide, striking the pouches ahead of them and destroying the separation between the pouches and thereby reducing the effectiveness of the cooling function. Further, effective cooling is best achieved by keeping the pouches in a flat configuration and the transfer of the pouches between conveyors using the slide mechanism has the effect of balling up the pouches so that they are no longer flat and so that the cooling effect is lessened. Further, the pouches tend to assume a random orientation on the slide and tend to slide toward the center or side of the conveyor unit where they may catch or strike on the sides of the conveyor. Although rupture of the pouches is rare, it is generally preferable to keep the pouches under positive control, well separated and correctly oriented as a method of eliminating any chance of pouch rupture.
According to a second prior art proposal for transferring the pouches from one conveyor level to the next, a separate transfer conveyor mechanism is provided proximate the discharge end of the upper conveyor. In this arrangement, the separate transfer conveyor mechanism coacts with the discharge pulley of the upper conveyor to move the pouches around the discharge pulley and deposit them on the feed end of the next lower conveyor. While this arrangement represents an improvement over the slide mechanism, it also has a number of disadvantages. First, it represents a separate piece of machinery which requires either power take-off from the main conveyor or its own power source. Additionally, it is complicated, requiring, for example, its own set of rollers, drive motors, gears, tension pulleys, etc. Further, there is inherently a gap between the main upper conveyor of the evaporative cooler and the transfer conveyor mechanism and this gap may cause misalignment of the pouches, snagging of the pouches, or contamination of the pouches with debris.